Abrasive tool



March 11, 1958 I Q 2,826,014

ABRASIVE TOOL Filed'May 27, '1955 INVENTOR. ALBERT FIELD.

ATTORNEYS 2,826,014 ABRASIVE TOOL Albert Field, Dayton, Ohio ApplicationMay 27, 1955, Serial N0. 511,710 2 Claims. ((31. 51 -190) The present invention relates to abrasive tools employed for polishing and finishing metal and plastic materials, as well as a method for making such tools.

There are a number of places where an abrasive element, i. e. one that utilizes emery cloth or paper, of a particular shape and form, can be used to advantage. One such place is in connection with the lapping of centers, i. e. the removal of scale at the end centers of a shaft after the latter has been heated-treated for case hardening. These centers are turned to a 60 degree angle to fit the live and dead centers of a lathe and the slightest imperfection in the conical surface is sufiicient to cause the shaft to rotate eccentrically or at least to encounter undue wear at the movable surfaces.

It appears that during the heat treatment of the shaft a scale, perhaps due to oxidation, or for any other reason, is formed at one or more places within the center so that the scale is not uniform and the angular Opening becomes rough and loses the roundness that it had prior to the heat treatment. Various ways have been proposed for removing this scale, such as grinding with conically shaped Carborundnm wheels, but due to the small length of surface to be ground, i. e. the shortness of the active tip of the wheel that is used, this tip becomes worn after only a few operations and must be either redressed or completely discarded.

The primary object of the present invention is to provide an improved abrading tool which is not of the grinding wheel type but utilizes emery cloth secured to a base or foundation member of proper shape and size to be inserted within the center and having a non-broken conical periphery.

Inasmuch as the active surface of the tool Wears down quickly, due to the small area of the surface that is actually used, another object is to provide an abrading tool of the character mentioned, in which the active abrading surface can be readily removed from a base member and quickly replaced by a fresh surface of the same size, character and shape as the replaced surface.

Still another object is to provide an abrading tool of the character mentioned in which the active head of the tool is locked in position from the rotational standpoint but is readily detachable from the body portion of the tool in the lengthwise direction in order to facilitate the substitution of a new active head portion for the worn out portion.

A still further object is to provide a new and improved method for attaching an abrading surface or element to a base member. This particular object is carried out by providing a base member of plastic and utilizing an adhesive for bonding the abrading surface such as emery cloth or paper to the plastic base member.

Another object is to provide an abrasive tool in which the active portions are constituted of a relatively hard plastic, but the retaining or gripping portions are constituted of metal, the two portions of each tool being detachably joined together in the longitudinal direction but fixedly joined together in the rotational direction so that the plastic element can be withdrawn from the metal portion and a substituted plastic portion can be rigidly secured to the metal portion in the rotational direction. This particular object is carried out in brief by providing a keying effect between the metal and plastic portions of the tool.

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be replaced by a fresh surface while maintaining the body of the tool intact and without removing the latter from the gripping element which serves to rotate the tool.

Other objects and features will be apparent as the specification is perused in connection with the accompanying drawings, in which:

Figure l is an elevational view of the improved abrading tool; the object shown in dot-dash outline represents the collet of a lathe or other power-driven rotating member which serves to rotate the tool;

Figure 2 shows the conicalhead portion of the tool insection but with the main portion in elevation;

Figure 3 is a sectional view taken along line 3 -3 in Figure 2;

Figure 4 depicts the various parts of the tool in exploded form and showing the manner in which these parts are assembled together;

Figure 5 illustrates a circular piece of emery cloth out of which the conically shaped abrading surface is formed;

Figure 6 depicts the wrapping of the emery cloth about the head portion of the tool; while Figure 7 is 'a view similar to Figure 2 but illustrating the application of my invention to a cylindrical form of abrading member.

Referring more particularly to Figures 1 to 4, the tool comprises a main body or shaft portion indicated at l, which may be constituted of steel. This body portion terminates at its lower end in two tapered portions 2, 3 of which portion 2 has only a slight taper but portion 3 is tapered to a point, preferably on a degree angle. This angle is determined by the size of the angle of the average center on the end of a shaft (not The final object is to provide an abrading tool having an emery cloth surface and in which this surface can shown) and in which it is desired to remove scale or other imperfections within the center due to any number of reasons, such as in the case-hardening process in which, through oxidation or other causes, a non-uniform layer of the metal clings to the conical surface of the center opening.

As can be seen in Fig. 4, the taper at 2 begins at the shoulder 4 and proceeds in greater diameter toward the shank portion 1. Interposed between the taper portion 2 and the shank 1 there is a laterally extending plate 5 formed integral with the shaft and having two parallel edges 6 and preferably two curved ends 7. The shape of this plate can take any form asits purpose is to serve as a key or a dog for detachably securing an abrasive head 8 to the shaf This head is made of a plastic orany other hard, moldable and inexpensive material such as hard rubber. The head comprises two portions, the conical. portion 9 and a short cylindrical portion 10.

This head member is hollow and the conical portion 9 has a conical opening 11 (Fig. 2) therein which is the exact counterpart of the conical end 3 of the shaft 1. This conical opening in the head merges into a slightly tapered opening 12 in the cylindrical portion 10 of the head which conforms to the taper of the portion 2 of the shaft, so that as the latter is presented to the head 8 the portions 2 and 3 fit snugly within the corresponding openings in the head 8. The slightly taperedportion 2 of the shaft causes the latter to stick" within the head member 8 by a sort of wedging effect, while the conical end portion 3 serves as a foundation or support for the head member.

Inasmuch as these contacting members are of a round configuration, provision must be made to prevent the head 8 from turning on the shaft 1 and yet will allow the head to be detached from the shaft when substitution of the head is indicated. For this purpose a countersunk closed-end groove 13 is providedin the cylindrical portion 3:0 of the head member, the width of the groove corresponding to the distance between the edges 6 of the plate 5 and the ends of the groove being curved to correspond with the curvature of the end 7 of the plate. Thus, the latter can be readily inserted into the opening 13 and as the shaft 1 is turned the head 8 is caused also to turn.

The taper 2 and its corresponding tapered surface within the head give sufficient gripping eflfect to prevent the head 8 from dropping by reason of its own weight from the shaft 1, and yet not sufficient friction is developed at these surfaces to prevent the head from being forcibly withdrawn from the shaft by a pull in the lengthwise direction.

The abrasive surface is supplied by a layer of emory cloth formed in conical shape, as indicated at 14, and wrapped around the conical surface of the head 8. This abrasive cloth covering is secured to the head 8 by any suitable and well known adhesive or glue which retains its bonding effect under all given temperature and moisture conditions, the character of the adhesive depending on the type of plastic. The plastic is preferably of the thermoplastic acrylate type.

The wrapping around process and the sealing operation to the head 8 is shown in Fig. 6 and it will be noted that the edges of the comically shaped abrasive covering come neatly together so that as the entire tool is rotated, for example by means of a collet 15 of a lathe or in a vertical drill-press, the abrasive surface at the head 8 presents a true circular periphery.

It is apparent that the shaft 1, including its terminating tapered portions 2, 3, is subject to little or no wear since the latter takes place solely at the abrading surface 14. Thus, in practice, many heads 8 to which the emery paper covering has been secured, may be provided for each shaft 1 in operation so that as the abrasive surface 14 becomes worn out, it is merely necessary to pull the plastic head from the key and to insert a new head with a fresh abrasive surface. These plastic heads and their abrasive covering 14 can be made most inexpensively so that they are readily expendable and the shaft 1 can be used over and over again when new abrasive surfaces are furnished. It is apparent that any number of heads 8 may be provided with various coarseness of emery paper attached so that the operator can pick the particular head to be attached to the shaft 1 as may be most suited to the job at hand.

i In order to make the emery paper covering as inexpensively as possible, there is provided a disc 16 (Fig. 5) of circular configuration and having a diameter the same as the peripheral length of the cylindrical portion of the head 8. By cutting the disc 16 on the diametral line and folding it from the center out, it will be found that when the edges come together, as seen in Fig. 6, the angle left by the emery paper will be a true 60 degrees.

However, it will be understood that my invention is not limited to any angle of the conical portion 9, but the 60 degree angle which is normally used in connection with the centers of shafts is easily procured in the manner described in connection with Fig. 5.

Various forms of the active surface 14 may be employed within the contemplation of my invention. In Fig. 7 there is illustrated an abrasive surface taking a cylindrical shape. In this case the plastic or hard rubber member is indicated at 17 and this member, as in the case of that described in connection with Fig. 4, has the two tapered openings 18, 19 for receiving the ends of the shaft 1. The latter is locked in position from the rotational effect by means of the plate 5 which is inserted into a recess or groove of corresponding shape within the plastic head 17. In this case, a cylindrical form of abrasive covering 20 is employed, this covering being initially cut to a strip shape and secured in any suitable manner to the head member 17.

From the foregoing it is apparent that I have disclosed a new and improved abrasive tool that can be employed in connection with the lapping of centers of shafts after the latter have been subjected to intense heat and oxidation during the case-hardening operation. The abrasive tool may take on any form or shape, depending on the work to be done but, in general, the head or active end of the tool is constituted of an inexpensive abrasive element which is detachable from the main body of the tool when pulled in the longitudinal direction but are rigidly held together during the rotating operation. The head is constituted of inexpensive material, easily fabricated by a molding operation, the abrasive cloth readily applied and the head is disposable when the abrasive surface becomes worn.

It will be understood that various modifications and arrangements in structure could be made without departing from the spirit of my invention and, accordingly, I desire to comprehend such modifications and substitutions of equivalents as may be considered to come within the scope of the appended claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. An abrading tool comprising a shaft having two tapered end portions adjacent one another, one of said portions having only a slight taper and the other having a greater taper and terminating in a point, a hollow memher having a conically shaped bore formed of two differently tapered portions coinciding with the tapers of the shaft, a key element secured to the shaft at the base of the slight tapered portion and extending transversely thereof, a slot in said hollow member extending across the bore of slight taper, said slot having a shape and size as snugly but detachably to secure said key element when the conical opening of said hollow member is presented to the tapered portions of the shaft, the taper of greater amount being such as to locate the member centrally on the shaft while the key member is being inserted into the slot, and the taper of slight amount being such as to cause the member to be tightly but detachably gripped by the shaft when the key has been completely inserted into the slot, and an abrasive layer attached to the exterior surface of said hollow member.

2. An abrading tool comprising a shaft terminating at one end in two tapered portions adjacent one another, the outermost end portion having a taper of approximately to a point and the inner portion having a less degree of taper, a hollow member having a conically shaped bore formed of two differently tapered portions coinciding with the tapers of the shaft, an element of rectangular and fiat configuration secured perpendicularly to the shaft at the position where the taper of less degree joins with the shaft portion of uniform diameter, said element extending transversely of the shaft, a rectangular slot of a depth corresponding to the depth of said rec tangular element in said hollow member across the bore of less taper, said slot being of a size and shape as snugly but detachably to receive said element in order positively to fix the rotational position of the element with respect to the shaft when the conical opening of th hollow memher is presented to the tapered portions of the shaft, the 60 end taper of the shaft being such as to locate the member centrally on the shaft while said rectangular element is being inserted into the rectangular slot, and the bore portion of less taper having a taper such as to cause the member to be tightly but detachably gripped in the longitudinal direction by the shaft when the rectangular element has been completely inserted into the rectangular slot, and an abrasive layer attached to the exterior surface of said hollow member.

References Cited in the file of this patent UNITED STATES PATENTS 2,181,474 Berger Nov. 28, 1939 2,489,722 Reich Nov. 29, 1949 2,537,252 Andersen Ian. 9, 1951 

